PROJECT SUMMARY The development of alcohol use disorders (AUDs) follows a transition from social use motivated by hedonic and anxiolytic effects to dependence-induced drinking motivated by the desire to alleviate the negative emotional state created by drug abstinence2,3. Enduring changes in brain function including compromised reward and heightened stress systems induced by repeated excessive alcohol intake underlie this functional shift from positive to negative reinforcement29. Converging evidence from human and rodent studies point to the concurrent impairment of executive function mediated by the medial prefrontal cortex (mPFC) and overactivation of stress systems within subcortical limbic structures including the basolateral amygdala (BLA), two reciprocally connected regions6, as key factors in the transition to alcohol dependence. The CRF/CRF1 system, critically implicated in anxiety and alcohol dependence, is prominently expressed in the mPFC. Indeed, activation of CRF/CRF1 signaling underlies stress-induced executive dysfunction22,23, selective deletion of forebrain CRF1 in glutamatergic neurons reduces anxiety24, and ethanol withdrawal leads to the activation of CRF neurons in the mPFC25. Therefore, CRF1 expressing neurons in the mPFC are poised to mediate behaviors driving ethanol dependence such as compulsive ethanol intake and heightened anxiety-like behaviors and likely undergo specific neuroadaptations induced by ethanol dependence. The objective of this proposal is to examine neuroadaptive changes in excitability and the functional connectivity of BLA inputs onto CRF1 expressing (CRF1+) and non-expressing (CRF1-) mPFC neurons in nave, ethanol dependent and withdrawn mice and to probe the contribution of CRF1+ neurons to anxiety-like behaviors in nave and withdrawn mice. To this end, we will utilize CRF1-GFP and CRF1-Cre mice to identify and manipulate CRF1 expressing mPFC neurons, optogenetics to selectively activate BLA inputs in the mPFC, in vitro slice electrophysiological recordings, and chemogenetics in combination with behavioral testing. The findings from these experiments will provide information about the functional connectivity between BLA inputs onto distinct pyramidal neuron populations, CRF1+ and CRF1-, in the mPFC and will provide insight into the neuroadaptations in this circuitry induced by ethanol dependence as well as the contribution of CRF1+ mPFC neurons to anxiety-like behaviors, potentially identifying novel therapeutic targets for the development of more efficacious treatment strategies for AUDs.